Solution on the horizon for green power’s erratic electricity

A constantly fluctuating electric current is one of the biggest technological hurdles to the widespread use of renewable energy sources. But a new research institute in Fukushima Prefecture may have a solution.

In April, the National Institute of Advanced Industrial Science and Technology, or AIST, opened its Fukushima Renewable Energy Institute in an industrial park in the northern prefecture.

FREA, as the new institute is also called, boasts rows of solar panels and a huge windmill on its premises. Researchers are using them to develop technology to control the often variable current produced by renewable energy sources.

Solar and wind power, which are vulnerable to constantly changing weather conditions, are plagued by wild fluctuations in the amount of power generated. If such an unstable flow of electricity enters the grid, it could cause serious trouble to home electric appliances and factory equipment by, for instance, disrupting the frequency of electricity and thereby causing changes in the rotation rates of motors.

Hydrogen solution

This poor quality of electricity generated is the biggest problem with green power generation.

But hydrogen could offer a solution, according to Yoshiro Owadano, director-general of the Fukushima institute.

The element plays a vital role in the renewable power system envisioned by the institute. When the system generates too much power, surplus electricity is used to produce hydrogen through the electrolysis of water. The hydrogen is then stored in liquid form, and when the system fails to generate enough power, it is fed to fuel cells to produce electricity. This would stabilize the current flowing into the power grid. Hydrogen is a particularly good storage medium as it is capable of storing a larger amount of electricity for a longer period of time than a fuel cell.

But the unstable flows generated by a renewable energy system could turn even simple electrolysis into a technological challenge by threatening to destroy the electrodes.

The first goal of FREA’s project is to develop technology to mitigate fluctuations in the amount of power generated and to create more durable electrodes.

Working with the National Renewable Energy Laboratory of the U.S., FREA is seeking to make these technologies available for practical use within three to four years.

Banking on batteries

Meanwhile, fuel cell technology has made significant progress in recent years and is now useful for large-scale power generation systems.

Hokkaido Electric Power plans to install large-capacity fuel cells in its major transformer substations next year. The utility will use the world’s largest redox flow battery developed by Sumitomo Electric Industries. A redox battery is an electrochemical fuel cell that relies on oxidation and reduction between two active materials on the surface of inactive electrodes.

Sumitomo Electric’s redox flow battery can store 60,000 kilowatt-hours of electricity, enough to power 6,000 households for a full day. The life cycle of the battery is 20 years. Installing the battery is expected to cost 20 billion yen ($193 million), and the government will subsidize the project.

If production of redox flow batteries increases significantly to meet demand from plants and other facilities, the cost would fall by more than 30% over the next three to four years, according to Junji Ito, managing director at Sumitomo Electric.

Ripe for the picking

There has been a surge in global interest in renewable energy, both to save resources and to cut greenhouse gas emissions, but numerous technological hurdles still stand in the way.

NGK Insulators is a pioneer in the development of large-capacity storage batteries. The sodium-sulfur (NaS) battery developed by the company can generate 1 kwh of electricity at a cost of some 40,000 yen, about one fifth the cost of a lithium-ion battery.

NGK controls 40% of the market for NaS batteries in California. The U.S. state has been keen to promote renewable energy, and major electric utilities there are required to introduce storage batteries into their facilities.

Last year, the Japanese company won the contract to supply NaS batteries to a major Italian power transmission company.

The global market for large-capacity storage batteries for substations and solar and wind power generation systems will be worth 263.3 billion yen in 2025, a 5.6-fold jump from last year, according to a prediction by Fuji Keizai, a Tokyo-based research firm.